The Pan-Arab colours are black, white, green, and red. Individually, each of the four Pan-Arab colours were intended to represent a certain Arab dynasty, or era. The black was the colour of the banner of Muhammad and the Rashidun Caliphate; white was used by the Umayyad Caliphate; green was used by the Fatimid Caliphate; and red was the flag held by the Khawarij. The four colours derived their potency from a verse by 14th century Iraqi poet Safi Al-Din Al-Hilli: « White are our acts, black our battles, green our fields, and red our swords ».
Pan-Arab colours were first combined in 1916 in the flag of the Arab Revolt. Many current flags are based on Arab Revolt colours, such as the flags of Jordan, Kuwait, Palestine, the Sahrawi Arab Democratic Republic, and the United Arab Emirates, and formerly in the flag of the brief six month union of the Arab Federation of Iraq and Jordan.
It may be noted that while Libya is an Arab country and has a flag with the same four colours, the colours have a different origin in this flag and are therefore not considered pan-Arab colours.
From the 1950s onwards, a sub-set of the Pan-Arab colours, the Arab Liberation colours, came to prominence. These consist of a tricolour of red, white and black bands, with green given less prominence. The Arab Liberation colours were inspired by the use of the Arab Liberation Flag in the Egyptian Revolution of 1952. These appear in the current flags of Egypt, Iraq, Somaliland, Sudan, Syria, and Yemen, and formerly in the flags of the rival states of North Yemen and South Yemen, and in the short-lived Arab unions of the United Arab Republic and the Federation of Arab Republics.